Patent GB-654092-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/42
Filed: 1948-02-20
Abstract: 654,092. Automatic telephone systems. WESTERN ELECTRIC CO., Inc. Feb. 20, 1948, No. 5091. Convention date, Aug. 18, 1944. [Class 40 (iv)] A telephone system comprises several automatic exchanges with means for making outgoing trunks of a group in considerable demand unavailable for automatic selection and means for automatically routing an incoming trunk to a manual board when pulses of an unavailable group are received and means in the manual board for routing the incoming trunk to an idle trunk in the unavailable group. The invention is concerned with enabling operators to establish connections in conditions of heavy traffic. The system is first described schematically with reference to Figs. 1 and 2, and then in greater detail with reference to the circuit drawings which should be assembled as shown in Fig. 36, those figures in parentheses not being used in the Abridgment. The Figure in which relays are to be found or in which leads originate are indicated by the number of hundreds in the reference.  General description.-A request for a toll call from a subscriber 100, Fig. 1, passes through a local exchange 101 and is connected by a trunk 102 to an outward toll board 103, the operator of which makes a record of the request and initiates a toll call which actuates an incoming trunk 105 of a cross-bar exchange of the type described in Specification 642,455, whereby the call is established to a distant exchange 111. If all trunks in the required outward group are busy, the marker 108 tests for and seizes any idle overflow trunk associated with the group, which signals the outward toll operator by flash that all the trunks in the group are busy. Normally, the operator holds the line, hoping that the overflow trunk will soon indicate, by a different flash, that a trunk has become idle, when the operator releases the line and makes a second attempt to complete the connection. If traffic is heavy and all overflow trunks are busy, the marker selects a master busy trunk 115 which transmits a master busy flash to the outward toll operator at 103 to indicate that considerable delay may be expected. The operator then prepares a ticket whereby an operator on a delayed outward toll board 104 can complete the call later. If a group of trunks shows considerable delay, a supervisor makes the group unavailable to toll operators and available only to a delayed outward operator, the overflow trunks being patched to a delay quotation circuit 118 and call order switchboard 120, the operator there announcing periodically the expected delay. The outward toll operator then disconnects and may dial special code numerals 151 to seize a special 151 trunk 123, Fig. 1B, to flash a lamp on the call order board 120, and the operator at 104 informs the operator at 120 of the desired connection, the operator at 120 preparing a call order ticket. Call order board. The  operator at 120 uses twin plugs on cords to make connection on a 4-wire basis with special trunks 123, 134, 136. The board also has a 10- button key-set whereby the operator can select an outgoing trunk through a sender and marker, as shown in Fig. 1C, the operator connecting up to the called and calling operators separately. The call order board has a number of single 3-conductor jacks and plugs for connection to the overflow trunks in which she is interested and any idle trunk associated with these overflow trunks flashes an appropriate lamp. Delay quotation. By observing lamps corresponding to overflow trunks on a traffic supervisory board and by observing the tickets in the call order board positions, the chief operator can estimate the delay expected and, when warranted, can patch the overflow trunks to a delay quotation group showing the estimated delay. Long distance call. A call from a distant key-pulsing toll board 202, Fig. 2, for a trunk on delay quotation automatically seizes a special 151 trunk 214 to gain access directly to a call order board. If, in such circumstances, the call order board is not occupied, the distant operator receives a signal that the desired trunk is on delay quotation, dials 151 and the call is automatically routed to a special 121 trunk 238 to gain access to a cordless switchboard 240, the operator of which prepares a ticket for an early connection in the manner shown in Fig. 1E. Fig. 2K, shows the system for serving calls from a manual toll office. Detailed description.-The usual Western Electric cross-bar system is followed, reference being made to Specifications 547,616, 653,002 and 654,096 and U.S.A. Specifications 2,241,016, 2,291,024 and 2,421,034. Signalling overflow to calling operator. Interrupters 533, 535 of different frequency intermittently operate and release relays 537, 538. Under overflow conditions, relay 555 is released and 537 connects interrupter 533 to operate relay 540 intermittently to signal through coil 503 to the calling operator that overflow has occurred. Normally, the operator holds on, hoping that a trunk will become idle, in which case relay 555 operates to connect relays 538 and interrupter 536 to relay 540 which then sends a re-order signal of different frequency. The operator releases the trunk to the exchange and makes another attempt to obtain an idle trunk to the desired destination.  Master busy trunk. If all trunks in a group and all associated overflow trunks are busy, a relay 425 (not shown) operates route switching mechanism whereby the marker is adjusted to operate master busy route relay 309 to cause the call to be transferred automatically to any master busy trunk which may be available and a flashing signal is transmitted to the calling operator who recognizes that this group of trunks is in considerable demand. Circuit request call. By sending out a special code 151, to operate a special route relay 312, the calling operator may light a lamp in the call order board, the operator of which answers the call by operating the talking key 803 and inserting twin plug 800 into jacks 723, 724 to operate a relay similar to 619 (not shown) in the calling exchange to indicate that the call has been answered. The calling operator requests an idle trunk in the desired direction and the call board operator investigates the condition of the trunk group by placing plug 567 into jack 564 to ascertain whether there is an idle trunk, overflow relay 555 releasing if one is available to cause interrupter 571 to flash a lamp 566 or 565 according to whether the idle trunk is suitable for short or long distance calls. The operator may then use plug 820 to complete the connection. If not trunk is idle, the call board operator writes a ticket to complete the call later. Delay quotations. A supervisory panel can be connected by jacks 509 to the overflow trunks and jacks 511 connected to the delay quotation circuit, when the supervisor thinks the delay and traffic requires such action. When this patching is effected, relay 522 pulls up to apply heating current to amplifier tube 514, and relay 541 energizes, whereby when a relay 504 operates in response to a call seizing an overflow trunk, relay 548 pulls up to operate 542, which supplies plate current to tube 514 and lights lamp 547. The operator throws the talking key 803 and inserts plug 800 into the delay quotation circuit jacks 527, 529 to operate relays 562, 563 which extinguish lamp 547. A telephone circuit relay 901 (not shown) also operates to associate the telephone set talking circuit with the delay quotation circuit and the operator announces the delay, after which she operates key À801 to cause the operation of relays 544, 548, whereby all relays 540 relating to overflow circuits patched to this delay quotation circuit are operated so that all the related calling operators receive the same signal. The calling operators then release their connections to the exchange to cause the release of relays 548, 542 and light the cord circuit supervisory lamp 809. The call board operator may then change the plug 800 to another delay quotation circuit to announce the delay expected on that group of trunks. Long distance calls. A call from a distant exchange operates a via only relay 317 in the marker and if the related trunk group is on delay quotation, the regular route relay 310 releases and a special 151 trunk group relay 312 operates, so that the marker tests the 151 trunks to give immediate access to the call board operator instead of requiring a second connection. Delayed quotations by cordless switchboard operators. In known manner, manual calls are connected to a cordless operator's position, which has a sender of the universal type operated by a key-set. Delays are announced normally but if the delay is considerable, the operator writes a ticket for a call order board operator or a special cordless operator to complete the call. If the cordless operator has attempted to complete a connection to a trunk group patched for delay quotation, a manual call for this direction is routed automatically to a master busy trunk to advise the calling operator that there is considerable delay. If the call order board is not manned, key 550 is thrown, and a distant operator makes a 151 circuit request call. It is automatically routed to a cordless operator by the operation of 121 route relay 311 instead of the 151 route relay 312. Completing toll connection from call order board. The call order board operators use special trunks, Fig. 20, for completing delayed calls. After observing an idle trunk in a patched group, the operator inserts twin plugs 820 of the cord circuit, Fig. 8, into jacks 2025, 2026 to initiate the actuation of a link, the selection of a sender and the connection of the trunk to the sender, followed by transmission of code pulses by keys in the call order board for selecting a trunk in the patched trunk group. One of the circuits established between the trunk and the sender causes the operation of a call order relay 3